1. Technical Field
The present invention relates to an image display device, an image display method, and a program.
2. Related Art
As the multimedia becomes more advanced, a display device has been developed to achieve a higher definition and a larger screen in recent years. For example, large-scaled direct-view liquid crystal display device, rear projection display device, and high-luminance image display device with a screen measuring 40 inches or more diagonally have been developed.
In order to improve the dynamic range and a contrast ratio of such a large-scaled image display device, an output of the backlight or lamp light source is increased, and the luminance is consequently increased further. Such an image display device, however, displays all the images while maintaining the output of the backlight or lamp light source to be constant. Hence, when used for a long period, such a large-scaled, high-luminance image display device raises a problem that elements, for example, a light valve, undergoes a color change or shortens its life due to overheating.
Meanwhile, there is an image display device in the related art that has a structure for controlling a light quantity from the backlight or lamp light source as described in the following paragraphs.
For example, JP-A-2004-157373 (page 5, FIG. 21) discloses an image display device that achieves an image display easy to see for the user through the display luminance modulation in addition to the improvements in image quality by preventing motion blurring by controlling the intermittent driving of the backlight light source or the black writing driving of the liquid crystal display panel in response to the illuminance of outside lights.
Also, JP-A-2001-175216 (page 1, FIG. 10) discloses an image display device comprising a display device using liquid crystals that achieves not only satisfactory grayscale reproducibility and color reproducibility, but also a grayscale display that remains stable over time and unsusceptible to a change in temperature.
Further, JP-A-2001-174919 (page 4, FIG. 1) discloses a projection-type image display device that can be readily reduced in overall size while being able to form a high-contrast, sharp projection image with ease in obtaining a satisfactory view image.
In each of the foregoing image display devices in the related art, however, the light control is performed to increase a contrast in a scene in which an entire image is dark. Hence, the contrast is increased by reducing an illumination light quantity to the light modulation element for such an image or a light quantity is adjusted in response to the environment lights in the surrounding. That is to say, the light source is subjected to the PWM (Pulse Width Modulation) to suppress motion blurring, which is the characteristic of the liquid crystal element. This raises a problem that the light control is not performed by taking the life of the elements forming the optical system into consideration.